A group of health experts this week asked Facebook to shut down a popular chat app aimed toward kids, saying that research shows that it will likely “undermine children’s healthy development.”

The letter was sent Tuesday by the Campaign for a Commercial-Free Childhood (CCFC), but signed by various other groups advocating for children to be free of social media. Addressed to Facebook CEO Mark Zuckerberg, the letter, pointedly takes the Menlo Park, California-based company to task for trying to bring society’s most vulnerable segment online too early.

Health experts to Facebook: Kids ‘simply not ready’ for social media

“Younger children are simply not ready to have social media accounts,” the letter says. “At a time when there is mounting concern about how social media use affects adolescents’ wellbeing, it is particularly irresponsible to encourage children as young as preschoolers to start using a Facebook product,” the letter says.”

The letter comes as tech mecca Silicon Valley endures significant push back from parenting groups and others about the targeting of its products and their privacy ramifications.

In early January, a group of investors sent a letter to Apple voicing strong concerns about the company’s reach among children and how it can better equip parents to stem device addiction. “We have reviewed the evidence and we believe there is a clear need for Apple to offer parents more choices and tools to help them ensure that young consumers are using your products in an optimal manner,” it reads in part.

Recent research shows that the more time children spend chatting on social sites such as Facebook, WhatsApp and Instagram, the less happy they feel about their lives. This not only affects their schoolwork and family relationships, but can ruin their self-esteem.

Additionally, one of the main dangers with children being online is that they simply don’t possess the intellectual wherewithal to understand how privacy works in the digital age. That means criminals are specifically targeting them in many ways. Here’s how to spot trouble, according to the Federal Trade Commission:

2 signs that your child’s online identity has been compromised

If your child begins to get calls or bills from companies or collections agencies for items you have not requested or received.

If your child gets any correspondence from the Internal Revenue Service, especially about filing taxes or the agency informs you that the kid’s Social Security number was used on another return.

Money expert Clark Howard says one way parents can have peace of mind is that they take steps to freeze the credit of their children. Equifax and Experian allow credit freezes for children in all 50 states, while TransUnion only allows it in states that have specifically passed laws on it. Learn more about how TransUnion handles child ID theft here.